The eastbound side of U.S. 36 that collapsed in mid-July in Westminster will reopen for Wednesday morning’s rush hour, the Colorado Department of Transportation has confirmed.

Significant damage on U.S. 36 caused by sub-structure and settlement issues is visible in Westminster on July 15, 2019.

A rebuilding project tackled the affected section at breakneck speed following the collapse, which has been blamed on a “slope failure” in the raised approach to a railroad overpass north of Church Ranch Boulevard. The project likely will continue for a couple more months, but CDOT officials say the new road surface is just about ready for the three lanes of traffic the section previously carried — two general-purpose lanes and one tolled express lane.

CDOT spokesperson Matt Inzeo said Friday that by Wednesday’s morning commute, the two free lanes will reopen on the eastbound side. The toll lane is set to reopen Thursday. The westbound side will have all three lanes open beginning Thursday morning, once the temporary barriers have been removed.

Since the highway’s partial closure, eastbound traffic has shared space on the westbound side of U.S. 36 in a temporary configuration between Wadsworth Boulevard and Church Ranch, with two lanes in each direction.

The highway’s full reopening will require single-lane closures, in both directions, overnight Tuesday and Wednesday.

CDOT has worked with contractor Kraemer North America, which won an emergency contract, to rebuild the embankment, retaining wall and highway pavement.

They stuck to the aggressive schedule they set in late July, working virtually around the clock.

“Every time I went out to the project, you could just tell there was a can-do spirit, both on our team and on the contractor team working on the site,” said Shoshana Lew, CDOT’s executive director, in an interview.

Because officials have cited the shifting of clay-heavy soils in the highway’s failure — which began with the appearance of large cracks that were noticed July 11, then escalated as a 200-foot section collapsed — crews rebuilt the section using different materials.

Crews drilled a series of caissons down into bedrock and placed 6,000 blocks of geofoam, measuring slightly more than 25,000 cubic yards in volume, as a substitute for dirt. Geofoam weighs 98 percent less than the soil it replaced, CDOT says, but can absorb the same downward pressures from the roadway above.

CDOT and its contractor Kraemer North America worked on rebuilding eastbound U.S. 36 by placing geofoam blocks along the section of the collapsed highway in Westminster on Sept. 5, 2019. About 6,000 foam blocks were placed before installation of new highway pavement on top.

CDOT expects a temporary bike lane to open Wednesday morning on the shoulder of the eastbound side of the roadway, separated from traffic by concrete barriers. A news release says to expect occasional closures of the bike path for some construction activities.

The Colorado Transportation Commission set aside about $20.4 million for the response to the emergency and for the reconstruction project, but CDOT hasn’t released a final cost accounting.

“We are just thrilled to be able to get this road back into service,” Lew said. “We see the success of this project as both good project management and excellent operation and maintenance of the interim traffic configuration.”

Still unresolved is the question of who ultimately will be on the hook for the costs. CDOT hired an outside firm, CTL Thompson, to investigate the causes of the highway collapse, and that probe is still underway.

The earthen wall that failed was mechanically stabilized, and it was built in 2013 under a standard contract as part of the first phase of a large-scale U.S. 36 expansion that added the toll lanes. But since then, the roadway has been managed under a public-private partnership contract with Plenary Roads Denver, which operates the toll lanes and maintains the entire roadway.

Another uncertainty is whether Plenary will seek reimbursement for lost toll revenue in that section since July.

Finishing touches on the rebuilding project that are still underway, likely until December, include installation of remaining concrete caissons, building of a permanent bike trail along the highway and installation of large panels on the new retaining wall.

Jon Murray is an enterprise reporter on The Denver Post's government and politics team, with a focus on transportation. He previously covered Denver Mayor Michael Hancock and city government. A Colorado native, he joined The Denver Post in 2014 after reporting on city government and the legal system for The Indianapolis Star.